1. Field of the Invention
In a multiple station intercom and telephone system the stations are interconnected through paired conductors which simultaneously handle voice communications and control functions on the intercom bus. Central office or PBX paired conductors may be connected to all telephone stations in the same order, or each telephone station may be connected so as to have a unique combination of central office or PBX lines available to the system.
2. Description of the Prior Art
Previous multiple station telephone and intercom systems (key systems) have utilized separate conductor pairs for signalling and control function isolated from any audio communications. These systems have also included a centralized control unit using either hook-flashing or other signaling schemes as the data transmission medium.
In prior art systems using centralized control, expansion of the system by adding new stations required some degree of modification of the central control unit.